The requirement can be thought of as of tile cropping the original page. I think the following command does what you want:
convert -density 288 HarrimanTrailMap.pdf -crop 20% +repage HarrimanTrailMap-tiled.pdf
You'll need imagemagick and ghostscript installed. Also, you mightmay encounter authorisation error when converting PDF files, have a look at https://stackoverflow.com/a/52863413/1921546 to resolve that.
If you feel that the resulting tiled PDF has less resolution, increase the -density value.
You can specify the -crop parameter by considering the number of tiles you want to split the original page into. Here, the original page is split into 5x5 tiles so it is cropped at 1/5=20% horizontally and vertically.
For more information about the command see the following link https://legacy.imagemagick.org/Usage/crop/#crop_tile